New boiler not big enough

Sharky127 · 29 Jan 2021

Hi,

I moved into a new property in September and the boiler went the first time we used it in earnest a month later. Sadly it had been serviced in the past 12 months so we didn't have an indemnity plan in place. Consequently i had it replaced and moved from the old airing cupboard in my daughters bedroom up into the loft.

The new boiler is a Worcester 2000 GC20000iW 25mW but we've found that it doesn't heat the whole house up? We have a 3 bed house with the garage converted into an office and dining room and 11 radiators in the property. The rooms in the original part of the property get warm but we get very little heat to the office and then none into the dining room or conservatory. At first i thought it could just need balancing and the pipes flushed through but i've subsequently had a plumber round who spent 2 days replacing the valves in the 3 rooms, completely flushing them out (really dirty inside), and rebalancing the system but to no effect and i'm now stuck with a freezing and unuseable dining room/conservatory so that we have to give our young son breakfast on a rug in the living room!

Does anyone have any suggestions as to what could be done to improve things or am i stuck looking at having to shell out for a more powerful boiler??

Thanks in advance for any help or advice offered.

terryplumb · 29 Jan 2021

Is your issue that some radiators just do not heat up at all ? Or they do heat up , but by feeling their heat by hand ,are not as hot to touch as other radiators ?
And finally ,did previous boiler heat all radiators fully ?

kidgreen61 · 29 Jan 2021

I wonder if you're the victim of a DIY/ builder plumber who's extended the pipes using long lengths of 10mm pipe which will be incapable of carrying enough water to furthest rads?
As Terry says, did they work before?
A 25Kw boiler should have plenty of capacity for 11 rads assuming they're not all massive doubles.

Sharky127 · 29 Jan 2021

The radiator in the office gets warm at best, the dining room is barely noticeable (warm to the pipes) and the conservatory is cold to the touch. I don't now if they worked before as we never used them until the day we first turned the heating on and then the boiler went. I've asked the previous owner and he said they did (he was hardly likely to say didn't).

Only the living room radiator is a double. What do you think i can do about it if anything? I'm currently having to run an electric heater out there which is costing a fortune so instead i sit under a duvet when i want to play on my PS4 at night!

terryplumb · 29 Jan 2021

Seems to me that the boiler installers need to address the problem . They should be able to determine why the system isn't working and advise you accordingly.

sxturbo · 29 Jan 2021

something wrong with the system somewhere, has the balancing definately been done correctly, there is a lot of plumbers that just p iss about witht hte trv and dont actually do any balancing.

an example, i have an 18kw boiler running 11 rads, and 9 of them are big doubles.

oldbutnotdead · 29 Jan 2021

First thing to try is shut off all other radiators except the 2 in the garage conversion. For a quick and dirty test like this, turn all the other rads off at their TRVs, turn the 2 cold ones up to full on their TRVs AND open the lockshield valves fully on those 2 (count how many turns with the spanner you need to open them, write that down somewhere). Now fire the heating up (timeclock on, roomstat set to max) and see what happens.
Some general things to look at- the room thermostat ideally should be in the hallway, the rad in there should not have a TRV on it.
The boiler shouldn't be cycling on and off frequently- from cold, an hour burn should get the place up to temperature. May be worth checking that the boiler is set to run at its full capacity (the installers should have done that but they should also have made sure the system was working properly before they left).
As someone pointed out, it is quite likely that the rads in the garage conversion are fed by undersized pipes thrown in by bodgers, they may even be airlocked.

D_Hailsham · 29 Jan 2021

Sharky127 said:
I don't now if they worked before as we never used them until the day we first turned the heating on and then the boiler went.

So the TRVs could all be stuck closed or partly open. Remove all TRV heads and check that the pin in the metal body can be pressed down without sticking and returns when released.

If the pins all work correctly, but radiator temperatures are different, the system needs to be balanced.

ianmcd · 29 Jan 2021

Sharky127 said:
The new boiler is a Worcester 2000 GC20000iW 25mW

That made me laugh it is 25KW and big enough

Sharky127 said:
who spent 2 days replacing the valves in the 3 rooms, completely flushing them out (really dirty inside),

The system should have been properly flushed when the boiler was moved

Sharky127 said:
i've subsequently had a plumber round who spent 2 days replacing the valves in the 3 rooms,

Hope you havent paid them

Get someone in that knows what they are doing , turn all rads off except one if that heats up then turn that off and open another one if that heats up close that and so on

Sharky127 · 29 Jan 2021

oldbutnotdead said:
First thing to try is shut off all other radiators except the 2 in the garage conversion. For a quick and dirty test like this, turn all the other rads off at their TRVs, turn the 2 cold ones up to full on their TRVs AND open the lockshield valves fully on those 2 (count how many turns with the spanner you need to open them, write that down somewhere). Now fire the heating up (timeclock on, roomstat set to max) and see what happens.
Some general things to look at- the room thermostat ideally should be in the hallway, the rad in there should not have a TRV on it.
The boiler shouldn't be cycling on and off frequently- from cold, an hour burn should get the place up to temperature. May be worth checking that the boiler is set to run at its full capacity (the installers should have done that but they should also have made sure the system was working properly before they left).
As someone pointed out, it is quite likely that the rads in the garage conversion are fed by undersized pipes thrown in by bodgers, they may even be airlocked.

The plumber that fitted the boiler tried this, when he couldn't get any heat out to the rooms he said to get new TRVs for those 3 radiators. I did this and got another plumber to try again. He did a full clean of the system and spent days trying to push the heat through by closing off all the other but without much success. It sounds to me like it might be the pipework to them and i don't think it's going to be very easy to rip the floor up to replace them.

More nagging from the missus due for me...my office is just about warm enough but she was in the dining room before the temp dropped and its simply to cold out there now and we don't want to be running an expensive electric heater as the conservatory roof needs to be replaced (another expensive job that needs to be done)

Sharky127 · 29 Jan 2021

ianmcd said:
That made me laugh it is 25KW and big enough

The system should have been properly flushed when the boiler was moved

Hope you havent paid them - It was my mates brother, who tbf was reasonable with the pricing and only paid cost for the parts but yeah, he must have known something was up as has since ignored all messages/calls hence having to get someone else in.

Get someone in that knows what they are doing , turn all rads off except one if that heats up then turn that off and open another one if that heats up close that and so on

ianmcd · 29 Jan 2021

What do you have in the way of room thermostats ? do you have one upstairs and one downstairs, or just one ? what programmer do you have ?

magicmushroom666 · 29 Jan 2021

If those rads dont get hot when everything else is shut then adding a bigger boiler wont fix anything. By shutting all the other rads off you've effectively created a 3 radiator system that any boiler would be big enough to run!
It sounds like more an issue with the pipework, installation etc.

Sharky127 · 29 Jan 2021

ianmcd said:
What do you have in the way of room thermostats ? do you have one upstairs and one downstairs, or just one ? what programmer do you have ?

Just one, it's a Worcester Comfort+ II RF

ianmcd · 29 Jan 2021

OK set the Heting to come on and post a pic of the boiler display with a demand for heating

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New boiler not big enough

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